Conventional disk drives generally utilize a stepper motor drive to move a read/write head assembly in a radial direction relative to the data tracks on the storage disk. In addition to data tracks, the disk generally includes one or more servo tracks which are read by the head assembly to provide a signal indicating actual head assembly position whereby accurate positioning of the read/write head assembly relative to a desired data track can be achieved. To provide initial alignment between the head assembly and a desired servo track, the head assembly drive of one type of conventional disk drive is mounted on a plate that rides in a slot in a casting member, and the head assembly drive is moved relative to the disk until a signal is generated that indicates that there is the desired alignment between the head assembly and the servo track. Once the desired alignment is achieved, the plate is fastened rigidly to the casting member.
The foregoing alignment is often carried out under temperature conditions that may fluctuate substantially from those encountered in disk drive operature. Temperature fluctuations often cause the disk to undergo dimensional distortions, such as, out of round, and such distortions can cause a deviation from the desired alignment between the head assembly and the servo track. Since the plate is fastened rigidly to the casting member in conventional disk drives, compensation for the aforenoted deviation cannot be effected.